1. Field of the Invention
The present invention relates to oxygen sensors.
2. Description of the Related Art
The exposure of hospital patients to infectious agents introduced by other patients is one of the most significant dangers in modern hospitals. As a result, hospitals have recently focused a great deal of energy on the prevention of such cross-contamination between patients. One problem in eliminating the danger of cross-contamination lies in the oxygen sensors currently employed in a variety of medical devices, such as anesthesia and ventilator circuits, aerosol tents, and the like. As will be understood, "breathing circuit" as used herein refers to a (non-electronic) circuit for carrying a flow of a gas.
Existing oxygen sensors typically employ a non-disposable, reusable galvanic cell for sensing changes in oxygen concentration. Existing galvanic oxygen sensors are based on the cathodic reduction of molecular oxygen at the working electrode and an oxidation reaction at the sacrificial anode. An example of the galvanic type cell is a cell made of a silver working electrode and a lead sacrificial anode with a KOH supporting electrolyte. These cells are typically self-powered.
One disadvantage of galvanic technology is the use of lead as the anode element, as lead constitutes a hazardous waste, and thus may be difficult or expensive to dispose of.
Such galvanic cells are relatively large and expensive to manufacture, and are thus typically reused many times with different patients. For these reasons the semipermeable membrane and related connecting components used in galvanic cells increases the possibility of patient cross-contamination because of its reusable characteristics. Such use may span an entire year and perhaps thousands of different patients. Although such sensors can be sterilized between uses, such methods are relatively expensive and burdensome. As a result, such sensors are often not sterilized between each use.
Consequently, ventilators, anesthesia machines, or other oxygen delivery apparatus may be exposed to oxygen sensors which may have been contaminated by any number of previous patients. Clearly, such existing oxygen sensors pose a substantial risk of cross-contamination between patients. In addition to the danger of cross-contamination, some gases, such as nitrous oxide, can cause premature oxidation of the silver working electrode, resulting in decreasing cell sensitivity over extended periods of exposure.
Given the potential for cross-contamination with existing oxygen sensors, there is a great need for a single-use disposable oxygen sensor that can be manufactured inexpensively and that can be disposed of safely so as to be disposable after a single use. Such a single use sensor would completely eliminate the danger of cross-contamination posed by existing sensors. Such a single use sensor would also eliminate the problem of decreased sensitivity caused by exposure to certain anesthesia gasses.
It is accordingly an object of this invention to overcome the disadvantages and drawbacks of the known art and to provide a single-use disposable oxygen sensor for use in a wide variety of oxygen dispensing devices.
It is a further object of the present invention to provide single-use oxygen sensor that contains little or no environmentally hazardous materials so as to be easily and safely disposed of.
It is a further object of the present invention to provide a single-use oxygen sensor that is small in size and is, therefore, easily portable and can be incorporated unobtrusively in a variety of oxygen-dispensing devices.
Further objects and advantages of this invention will become apparent from the detailed description of a preferred embodiment which follows.